DBMC-NOMA: Evaluating NOMA for Diffusion-Based Molecular Communication Networks

This paper presents an evaluation of non-orthogonal multiple access (NOMA) as a novel approach for diffusion-based molecular communication (DBMC) networks. The scheme draws from the example of power-domain NOMA in classical communication and relies on differences in the number of received molecules. It utilizes successive interference cancellation to separate simultaneously transmitted messages from multiple transmitters (TXs) at the receiver (RX) using a single molecule type. We analytically derive the bit error probability of a communication system using DBMC-NOMA with K TXs and a central RX and validate the model with Monte Carlo simulations. Our results show that the emitted number of molecules from each TX is a crucial parameter to optimize the performance of DBMC-NOMA. Additionally, we compare the performance of DBMC-NOMA against time-division multiple access (TDMA) and molecule-division multiple access (MDMA) with respect to the mutual information at the RX. The investigation shows that TDMA and MDMA act as the lower and upper performance bounds for DBMC-NOMA, respectively. For a sufficiently large molecule budget and SNR, DBMC-NOMA outperforms TDMA and matches MDMA using only one molecule type even as the number of TXs grows. These results show the potential of NOMA as an option for DBMC and the need for further analysis of power control schemes to optimize the number of emitted molecules in DBMC networks.